A collecting and folding cylinder is part of a folding apparatus. Three folding blade shafts, for example, are arranged on the collecting and folding cylinder. The folding blade shafts rotate around pivoting points which are distributed symmetrically over the cross section of the collecting and folding cylinder. Whereas the collecting and folding cylinder rotates around its center, the folding blade shafts rotate around their respective pivoting points as well. In so doing, they execute a hypocycloidal movement. Moreover, each folding blade shaft executes an oscillating movement which causes the folding blades arranged on it to project partially out of the folding blade cylinder in order to fold the sheets to be folded or to sink into the folding blade cylinder again. Because of this complicated sequence of movements it is necessary to arrange specially made sealing devices at the end face of the collecting and folding cylinder which prevent oil from escaping from an oil space in the interior of the collecting and folding cylinder at the sides of the front boundary of the folding blade shafts or to prevent dirt from penetrating into the interior of the folding blade cylinder.
A known solution to this problem consists in the arrangement of disk-shaped plastic rings of different diameters. The plastic rings execute a sliding and rotating movement relative to one another, which results in a heating of the plastic rings particularly at high folding speeds. As a result, they are deformed in a plastic manner and spring out of their guides. They wear out quickly and can tall into the interior of the folding blade cylinder and cause damage there. Moreover, oil escapes at the sides of the folding blade shafts. It is an object of the present invention to provide a reliable and wear-resistant sealing for a collecting and folding cylinder.
This object is met by providing an end-face sealing assembly surrounding a folding blade shaft in a folding cylinder, the end-face sealing assembly having a covering disk and an additional disk made from metal. Specifically, there is provided a folding cylinder with an interior oil space and a plurality of folding blade shafts arranged at a distance from one another at its circumference and constructed for executing hypocycloidal movements. Each folding blade shaft carries a disk having a bearing. The disk has a sealing ring arranged on the collar of the side facing the oil space of the folding cylinder and can be pressed against a covering disk by a clamping ring arranged on the folding blade shaft, and wherein the covering disk is arranged eccentrically on the shaft, runs in a bearing race via bearings, and is rotatably connected with the disk via a bearing and a stud.
In an advantageous further development, the folding blade shaft is enclosed by a clamping ring which presses the additional disk against the covering disk. In another advantageous construction the covering disk has a sealing ring on its collar, which sealing ring seals the interior of the folding cylinder relative to the covering disk so as to be tight against oil. This prevents oil from spraying out at high rates of rotation of the folding cylinder. Preferably, a sealing ring is also arranged at the collar of the additional disk to seal the space between the coveting disk and the additional disk. The coveting disk and the additional disk are preferably made from aluminum. The surface of the covering disk facing the additional disk is preferably hardened.